The Research Of Three-dimensional Reconstruction Of Underground Channel Based On Close-range Photogrammetry

Digital Close-Range Photogrammetry is usually used in the reconstruction of surface buildings, the theory and practical application of which are more mature. However, the research of reconstruction of the building in the underground is less, because it is not an independent entity, and it must be taken photos in its internal. This paper reconstructed three-dimensional model based on images obtained from general digital camera of the underground channels, and carried on research mainly from the following areas:(1)Underground control field is established by control points. This section focuses on the selection of artificial landmarks, layout principles and the method of building Object Space Coordinate System. Data collection came from general digital camera and total station.(2)General digital camera is calibrated using the model plane grid, calculated optimal solution of the camera parameters by analyzing linear model and then carryed on nonlinear refinement based on the maximum likelihood method. Calibration shows that experimental digital camera is stable and can be used in three-dimensional reconstruction of underground channels.(3)Laborious research about Feature extraction, image matching, bundle adjustment method and theory are done and then experiments are given.(4)The points and lines of sufficient overlap of the photograph are reconstructed, using photogrammetric knowledge about double resolution, and the three-dimensional model is measured. Experimental results show that this method has high accuracy.(5)The relationship between the OpenGL imaging matrix and the orientation elements of photogrammetry is created through the derivation of the OpenGL's perspective. The instance shows that OpenGL can simulate the images that the parameters are known. The result provides a new research direction for photogrammetric data processing, accuracy assessment and so on.Initial results obtained through research, close range photogrammetry for the future underground passage in the research and application of three-dimensional reconstruction to play down a good foundation, have broad application prospects. Initial results obtained from the research, play a good foundation for the research and application of three-dimensional reconstruction in underground passage and have broad application prospects.